Iran has virtually halted a previously rapid expansion of its uranium enrichment capacity in the past three months, the U.N. nuclear agency said in a report roughly covering the period since moderate Hassan Rouhani became president. The quarterly report by the International Atomic Energy Agency (IAEA) also showed that Iran's stockpile of higher-grade enriched uranium - closely watched by the West and Israel - had risen by about 5 percent to 196 kg since August. The IAEA said Iran had installed only four first-generation centrifuges - machines used to refine uranium - at its Natanz plant since August, making a total of 15,240.